PB1899: OUTCOMES OF PATIENTS UNDERGOING TREATMENT FOR ACUTE MYELOID LEUKAEMIA SHOWING HIGH DEGREE OF PREDICTIVE ACCURACY ON THE EUROPEAN LEUKAEMIA NET (ELN) POST-REMISSION TREATMENT SCORE
Authors: Michelle Richardson, Chrishthuka Kangatharan, Sheraz Bashir, Victor Ling, Hafsana Siddique, Jayne Chappells, Joanne King, Isobel Chalmers, Andrew Hodson, Mahesh Prahladan
Journal: HemaSphere (2023)

Topic: 4. Acute myeloid leukemia - Clinical Background: The European Leukaemia Net (ELN) post-remission treatment (PRT) score in patients with Acute Myeloid Leukaemia (AML) is a prognostic tool that was developed based on the association between potentially prognostic (baseline) variables and overall survival after complete remission. The PRT score takes into account CD34 and FLT3-ITD mutant-to-wild-type ratio, which are factors not considered in the 2022 ELN risk stratification. Aims: The aim of this study is to evaluate the accuracy of the ELN PRT score in predicting overall survival and to compare it to the 2022 ELN risk stratification criteria. Methods: We conducted a retrospective analysis of 51 AML patients who were treated at our institution between January 2018 and December 2022. Out of these, 9 patients were included in the study as they fit the eligibility criteria (aged 15 to 60-years-old) and had achieved complete remission after intensive chemotherapy or hematopoietic stem cell transplantation. We calculated the AML post-remission treatment (PRT) score for each of these 9 patients using the criteria established by the Study Alliance Leukemia (SAL) in the AML96 trial. The PRT score takes into account several prognostic factors including CD34 blast percentage and FLT3-ITD mutant-to-wild-type ratio. We then compared the PRT score with the 2022 European Leukemia Net (ELN) risk stratification criteria, which uses only molecular and cytogenetic abnormalities to categorize AML patients into three risk groups: favorable, intermediate, and adverse. We assessed the prognostic accuracy of the PRT score by calculating the overall survival (OS) and progression-free survival (PFS) of the patients in our study. Results: Of the 9 patients included in the study, 5 fell under the favourable-risk group based on the ELN PRT score, 3 fell under the intermediate-risk group, and 1 fell under the adverse-risk group. The median OS for the favourable-risk group was 673 days, compared to 317 days for the intermediate-risk group and 290 days for the adverse-risk group. The median PFS for the favourable-risk group was 328 days, compared to 144 days for the intermediate-risk group and 177 days for the adverse-risk group. Based on our analysis, we found that the overall survival more accurately reflected the patients’ risk groups according to the ELN PRT score, rather than the 2022 ELN risk category. Patients who fell under the favourable-risk group according to the PRT score had a better overall survival compared to those who fell under the intermediate or adverse-risk group, regardless of their 2022 ELN risk category. These findings suggest that the ELN PRT score may be a more accurate predictor of overall survival in AML patients compared to the recent 2022 ELN Risk Stratification Criteria, when applicable. Summary/Conclusion: Our study confirms the accuracy of the ELN PRT score in predicting overall survival after complete remission in AML patients. The inclusion of CD34 and FLT3-ITD mutant-to-wild-type ratio in the ELN PRT score provides more accurate risk stratification than the 2022 ELN criteria, which only considers molecular/cytogenetics abnormalities. Therefore, we recommend using the ELN PRT score whenever possible to guide treatment decisions in AML patients aged 15-60. Keywords: Prognostic factor, Acute myeloid leukemia, ELN, Clinical outcome